Sleep mode operation for networked end devices

ABSTRACT

A technique provides apparatuses, methods, and computer readable media for sending sleep information from an end device to a central unit of a network, in which the wake-up time of the end device is aligned to the scanning time for the central unit. The technique addresses at least two considerations: the clock accuracy of the end device is accounted for, and the reason that the end device requests sleep mode operation is provided. To address the above considerations, the end device may send its clock tolerance information and/or request for sleep mode (RSM) command to the central unit once the end device is connected via the network. The central unit may then adjust the scanning time based on the clock tolerance information. If the central unit receives a response from the end device during the adjusted scanning time, the central unit deems that the end device is still connected.

FIELD

Aspects described herein relate to supporting sleep operation fornetworked devices.

BACKGROUND

The number of networked devices (e.g., sensors, switches, andthermostats) is increasing at an explosive rate. For example, with the“Internet of things,” which may be referred as the “Internet of embeddeddevices,” factory control systems, medical devices, cars, the smartgrid, and communication systems are being deployed. Approximately 5billion embedded devices are now networked (year 2012) to the Internet.Projections suggest that the number will increase to 15 billion by year2015. In addition, additional networked devices are incorporated intoother private home and industrial networks. Because of the sheer numberof networked devices, as well as the often remote deployment of thedevices, techniques are incorporated to extend the operation of thedevices to reduce maintenance of the devices. One approach is for thedevices to operate in a sleep mode to reduce electrical powerconsumption of the networked devices. During the sleep mode, abattery-powered device operates at low power, often saving significantelectrical consumption and consequently extending the battery life.

With traditional systems, embedded devices may sleep and wake up for apredetermined period of time in order to save energy consumption. Thenetworked devices may be constantly scanned to verify the availabilityof the networked devices. However, this traditional approach may becharacterized by one or more deficiencies.

SUMMARY

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of the disclosure. The summary is not anextensive overview of the disclosure. It is neither intended to identifykey or critical elements of the disclosure nor to delineate the scope ofthe disclosure. The following summary merely presents some concepts ofthe disclosure in a simplified form as a prelude to the descriptionbelow.

With an aspect of the disclosure, a technique is supported for sendingsleep time from an end device to a central unit of a network, in whichthe wake-up time of the end device is aligned to the scanning time forthe central unit. The technique addresses at least two considerations.The clock accuracy of the end device is accounted for, and furthermorethe reason that the end device requests sleep mode operation is known.To address the above considerations, the end device may send its clocktolerance information to the central unit once the end device isconnected via the network. The central unit may then adjust the scanningtime based on the clock tolerance information. If the central unitreceives a response from the end device during the scanning time, thecentral unit deems that the end device is still connected.

An end device may provide sleep information about its sleep modeoperation in a number of ways. For example, the end device may send atime request to the central unit with a time value for operating in thesleep state. Alternatively, the end device may send a request for sleepmode (RSM) command to the central unit. The RSM command comprises a codethat is defined between the end device and the central unit. The centralunit may then determine the operating condition at the end device,action that should be performed for the end device, and the requestedsleep time.

With another aspect, a central unit determines a targeted energy usagefor a network, which may comprise a plurality of end devices. Thecentral unit then budgets energy consumption for each of the end devicesand sends a sleep mode request with an associated sleep time to each ofthe end devices.

Various aspects described herein may be embodied as a method, anapparatus, or as one or more computer-readable media storingcomputer-executable instructions. Accordingly, those aspects may takethe form of an entirely hardware embodiment, an entirely softwareembodiment, or an embodiment combining software and hardware aspects.Any and/or all of the method steps described herein may be implementedas computer-readable instructions stored on a computer-readable medium,such as a non-transitory computer-readable medium. In addition, varioussignals representing data or events as described herein may betransferred between a source and a destination in the form of lightand/or electromagnetic waves traveling through signal-conducting mediasuch as metal wires, optical fibers, and/or wireless transmission media(e.g., air and/or space).

Aspects of the disclosure have been described in terms of illustrativeembodiments thereof. Numerous other embodiments, modifications, andvariations within the scope and spirit of the disclosure will occur topersons of ordinary skill in the art from a review of this disclosure.For example, one of ordinary skill in the art will appreciate that thesteps illustrated herein may be performed in other than the recitedorder, and that one or more steps illustrated may be optional inaccordance with aspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary of the invention, as well as the followingdetailed description of exemplary embodiments of the invention, isbetter understood when read in conjunction with the accompanyingdrawings, which are included by way of example, and not by way oflimitation with regard to the claimed invention.

FIG. 1 shows a network with a central unit and end devices in accordancewith an embodiment.

FIG. 2 shows an end device in accordance with an embodiment.

FIG. 3 shows a central unit in accordance with an embodiment.

FIG. 4 shows a flow diagram for supporting a sleep mode for an enddevice by a central unit in accordance with an embodiment.

FIG. 5 shows a flow diagram executed by a central unit to process arequest for sleep mode (RSM) command from an end device in accordancewith an embodiment.

FIG. 6 shows an example of associating status information received froman end device to an operating condition of the end device in accordancewith an embodiment.

FIG. 7 show an example of associating status information received froman end device to a sleep time value for the end device and action thatcan be initiated for the end device in accordance with an embodiment.

FIG. 8 shows a mapping of the device identification of an end devicewith the location of the end device in accordance with an embodiment.

FIG. 9 shows a flow diagram for a central unit configuring a sleep modefor an end device based on a targeted system energy usage in accordancewith an embodiment.

DETAILED DESCRIPTION

FIG. 1 shows network 100 with central unit 101 (which may be referred toas a coordinator or a gateway), routers 110-111, and end devices 102-109(e.g., a sensor, switch, or thermostat) in accordance with anembodiment. Network 100 may support one of different networkspecifications, including ZigBee®, Bluetooth®, and Z-Wave®. For example,Zigbee devices may be used in smart energy, medical, and home automationapplications. With smart energy applications, Zigbee products are oftenused to monitor and control use of energy and water, which helpsconsumers save energy and water and save money too. With medicalapplications, Zigbee may support connecting a large number of healthmonitoring devices. With home automation applications, Zigbee supportsthe control of domestic lighting, such as switches, dimmers, occupancysensors, and load controllers.

With some embodiments, central device 101 starts a personal area network(PAN) so that end devices 102-109 can join network 100 through routers110-111. Central device 101 may be responsible for selecting the channeland PAN ID. Central device 101 may assist in routing the data throughthe mesh network and allows join requests from routers 110-111 and enddevices 110-111. As will be discussed, central device 101 supports sleepmode operation of end devices 102-109 to reduce the overall energyconsumption of network 100. Central device 101 typically maintains itselectrical power and does not operate in a sleep mode.

With some embodiments, central unit 101 starts the joining process byassigning a PAN ID to network 100 Assignment may be done in differentways, e.g., manual (pre-configured) and dynamic (obtained by checkingother PAN IDs of networks already in the operation nearby so that PAN IDdoes not conflict with other networks). After central unit 101 completesits configuration, central unit 101 can accept network joining requestqueries from routers 110-111 and end devices 102-109 that wish to jointhe PAN.

With some embodiments routers 110-111 may be joined into network 100.For example, router 110 joins before end devices 105-106 and beforerouter 111 can join. Routers 110-111 typically maintain electrical powerand do not support sleep mode operation.

End devices 102-109 typically do not allow other devices to join network100, assist in routing data through the network 100, or support childdevices. End device 102-109 may be battery powered and may consequentlyoperate in a sleep mode operation so that the device 102-109 can foregotasks and reduce electrical power consumption, thus extending theoperating time of the device's battery.

There are different ways for end device 102-109 to join network 100. Enddevice 102-109 may join network 100 via a media access control (MAC)sub-layer or the network layer. Once central unit 101 has established apersonal area network, end device 102-109 determines whether centralunit 101 is allowing device to join network 100. For example, end device102-109 may send an association request frame and may join network 100as soon as end device 102-109 receives an association response. Centraldevice 101 may allow end devices 102-109 to join based on differentfactors, including the number of end devices that have already joined.

End devices 102-109 are often battery-operated so that the devices canbe operated independently from an AC power source. The battery life ofRF end devices 102-109 (networked devices) may be an important concernwhen operating network 100. With some embodiments, battery-operated RFend devices 102-109 will sleep and wake up for a pre-determined periodof time in order to reduce the energy consumption. Central unit 101(also referred as a gateway or coordinator), may need to determinewhether end device 102-109 is still in the network 100. With sometraditional systems, central device 101 can constantly scan network 100to check for the availability of end devices 102-109. This technique isoften called a “heartbeat” of RF wireless networking.

However, if end device's operation and wake up frequency depends on theenvironment or its status, e.g., at night or when battery has lowcharge, the fixed heartbeat technique may not benefit the battery life.Furthermore, if end devices 102-109 wake up all at the same time, theexcessive RF traffic may affect the transmission quality provided bynetwork 100 and result in transmission retries. This situationconsequently may affect the battery life of battery-power too.

FIG. 2 shows end device 102 in accordance with an embodiment. End device102 includes processing device 201, memory device 202, and networkinterface 203 that interfaces to network 100. At least one processingdevice 201 executes computer-executable instructions from memory device202 so that end device can provide the intended functionality, whereinthe processes discussed herein may be implemented, and can communicatewith central unit 101 via network 100. Processing device 201, whichincludes at least one processor, typically controls overall operation ofend device 102. Memory device 202 comprises computer-readable storagemedia that may be any available media that may be accessed by processingdevice 201.

Computer storage media include volatile and nonvolatile, removable andnon-removable media implemented in any method or technology for storageof information such as computer readable instructions, data structures,program modules or other data. Computer storage media include, but isnot limited to, random access memory (RAM), read only memory (ROM),electronically erasable programmable read only memory (EEPROM), flashmemory or other memory technology, CD-ROM, digital versatile disks (DVD)or other optical disk storage, magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices, or any othermedium that can be used to store the desired information and that can beaccessed by processing device 201. By way of example, and notlimitation, computer readable media may comprise a combination ofcomputer storage media and communication media.

Communication media typically embodies computer readable instructions,data structures, program modules or other data in a modulated datasignal such as a carrier wave or other transport mechanism and includesany information delivery media. Modulated data signal includes a signalthat has one or more of its characteristics set or changed in such amanner as to encode information in the signal. By way of example, andnot limitation, communication media includes wired media such as a wirednetwork or direct-wired connection, and wireless media such as acoustic,RF, infrared and other wireless media.

End device 102 may interface to a peripheral device 205 (e.g., a sensordevice and may be integrated with or external to end device 102) throughperipheral device 204. With some embodiments, peripheral device 205 maybe controlled by processing device 201 and/or provide input informationand/or support output functionality.

FIG. 3 shows central unit 101 in accordance with an embodiment. Centralunit 101 includes processing device 301, memory device 302, and networkinterface 303. At least one processing device 301 executescomputer-executable instructions from memory device 302 so that enddevice can provide the intended functionality, wherein the processesdiscussed herein may be implemented, and can communicate with enddevices 102-109 via network 100. Processing device 301, which includesat least one processor, typically controls overall operation of centraldevice 101. With some embodiments, the operation of memory device 302 issimilar to those of memory device 202 (as shown in FIG. 2) as previouslydiscussed.

Central device 101 may interface to display device 305 through userinterface 304 to notify a user about a course of action that may beperformed for a given end device. The display device may be integratedwith central device or external to central device 101. For example, ifthe end device's battery has a low charge, the user may be informed ondisplay device 305 that the battery should be replaced.

FIG. 4 shows flow diagram 400 for supporting a sleep mode of end device102 by a central unit 101 in accordance with an embodiment. With oneaspect, a technique is supported for sending sleeping time from enddevice 102 to central unit 101 (which may be referred to as a gateway orcoordinator) in which the wake-up time of end device 102 is aligned tothe scanning time for central unit 101. The technique addresses at leasttwo considerations. First, the clock accuracy of end device 102 isaccounted for. For example, if the sleep time is large and end device102 has poor clock tolerance on end devices, central unit 101 may missthe wake up of end device 102 when end device 102 sends a response.Second, central unit 101 may not know the reason that end device 102requests sleep mode operation so that corrective action is not performedin an expeditious manner.

To address the above considerations, end device 102 (e.g., a sensor,switch, or thermostat) may send its clock tolerance information tocentral unit 101 (e.g., hub, server, or gateway) for network 100 onceend device 102 is connected to central unit 101 via network 100. As willbe further discussed, central unit 101 may adjust the scanning timebased on the clock tolerance information.

End device 102 may provide sleep information about its sleep modeoperation a number of ways. For example, end device 102 may send a timerequest to central unit 101 with a time value for operating in the sleepstate. Alternatively, end device 102 may send a request for sleep mode(RSM) command to central unit 101. The RSM command comprises a code thatis defined between the end device 102 and central unit 101. For example,one RSM code may signify that the end device's battery is low. AnotherRSM code may denote that end device 102 is requesting sleep modeoperation because the end device is operating in night operation. Whenthe RSM code is received, central unit 101 may determine the sleep timeof end device 102 at initial setup. For example, central unit 101 maymap the amount of sleep time with the RSM code as shown in Table 2 (FIG.7), With some embodiments, central unit 101 may use a table (e.g., Table1 as shown in FIG. 6) to determine the operating condition at end device102 that is associated with the sleep request.

Central unit 101 may generate Table 1 in a number of ways, e.g., knowingthe table information a priori, obtaining the table information from enddevice 102, or obtaining the table information through a user interface.From the RSM code, besides extending the sleep time of end device 102,central unit 101 may determine what happened at end device 102 andconsequently can notify an end user to perform appropriate actions(e.g., Table 2 as shown in FIG. 7).

At block 401, end device 102 sends clock tolerance information about itsinternal clock to central unit 101. End device 102 may use the internalclock to determine when to wake up from sleep mode operation. When enddevice 102 wakes up, end device 102 may send to central unit 101(corresponding central unit 101 receiving the response at block 404) aresponse that may comprise a measurement message, an all-is-wellmessage, a sleep mode request, or some other specified message.

At block 402, central unit 101 obtains sleep information about enddevice 102. For example, end device 102 may inform central unit 101about the time when end device is in the sleep mode. The sleep time maybe expressed as a relative value (e.g., from a particular time), anabsolute value, or a periodic time (e.g., the end device going into asleep state every particular amount of time). As another example, aswill be further discussed, central unit 101 may receive a RSM code fromend device 102 that is indicative of the operating condition at enddevice 102. Central unit 101 may then map the code to timing informationabout sleep mode operation at end device 102. As will be discussed,central unit 101 may also send a sleep mode request for end device 102to go into a sleep state for a particular amount of time. Alternatively,central unit 101 may know a priori when end device 102 is operating in asleep mode or may be informed through a user interface.

At block 403, central unit 101 adjusts the sleep information to obtain ascanning time when central unit 101 should receive a response from enddevice 102. For example, if the clock tolerance of end device 102 were+/−5%, the wake up time may be adjusted by central unit 101 to wake upearlier in time by a factor of 0.95 of the expected time. Also, thescanning window may be increased by a factor of 1.1 of the expected scantime.

At block 404, central unit 101 scans for a response from end device 102during the adjusted scanning time. If central device 101 does notreceive a response within the determined time interval, at block 405central unit 101 determines that end device 102 is not connected tonetwork 100. This may be the case for different reasons. For example,end device 102 has been physically removed or end device 102 does nothave adequate electrical power that requires that the battery to bereplaced. With some embodiments, central unit 101 may generate anindicator so that a user can be informed about the situation. However,if central unit 101 does receive a response during the scanning time atblock 406, central unit 101 deems that end device 102 is still connectedto network 102.

FIG. 5 shows flow diagram 500 that is executed by central unit 101processing a request for sleep mode (RSM) command from end device 102 inaccordance with an embodiment. As discussed above, central unit 101 mayreceive an RSM command from end device 102 at block 501. The RSM code601 may be mapped to an operating condition 602 at end device 102 atblock 502, for example, using Table 1. For example, when RSM code 601equals “011”, the end device's battery is deemed as being “acutely low.”Also, the user may be notified on display 305 (as shown in FIG. 3) atblock 503 that the battery should be replaced based on the actioninformation 702 in Table 2. Also, sleep time 701 is extended to fourhours in order to reduce energy consumption when the battery is low. Asanother example, when the RSM code equals “101”, the operating conditionat end device 102 is related to a charging problem (based on Table 1,i.e., the battery is not charging properly because, for example, thereis not enough energy being harvested). In such a case, the user may beinformed to replace the charging circuit and/or reposition end device102 so that more energy can be harvested.

FIG. 8 shows Table 3 having a mapping of device identification 801 ofend device 102 with location 802 of end device 102 in accordance with anembodiment. While not explicitly shown in FIG. 1, network 100 maycomprise a large number of end devices. The end devices may be widelydistributed, may be dynamically relocated, and concealed to a user. Inorder facilitate track the location of the end devices, central unit 101may generate Table 3 so that central unit 101 can determine the locationof a responding end device based on device identification 801 containedin a response from the end device. The location information may then beincluded in a notification to user about action that should be performedat the end device.

FIG. 9 shows flow diagram 900 for central unit 101 configuring a sleepmode for an end device 102 based on targeted system energy consumptionin accordance with an embodiment. At block 901, central unit 101determines targeted overall energy consumption for network 100 over aperiod of time (T_(span)), e.g., an hour, day, week, or month.

Referring to FIG. 1, the consumed energy of network 100 is the sum ofenergy consumptions for central device 101, routers 110-111, and enddevices 102-109, where:E _(network) =E _(end-devices) +E _(routers) +E _(central) _(—)_(unit)  (EQ. 1)

Typically, operation of routers 110-111 and central unit 101 should notbe changed.

Consequently, only end devices 102-109 are modified to selectivelyoperate in a sleep mode in order to reduce energy consumption. With someembodiments, E_(network) is the targeted energy consumption of network100 while E_(routers) and E_(central) _(—) _(unit) are known a priori orare measured. In such a case, central unit 101 will modify sleep modeoperation of end devices 102-109 (corresponding to E_(end) _(—)_(devices)).

With some embodiments, the energy consumption of the i^(th) end device(E_(i)) may be determined from the energy consumed during sleep modeoperation (E_(sleep,i)) and the energy consumed during wake modeoperation (E_(wake,i)). The corresponding consumed power may be measuredor known a priori for each end device 102-109. Consequently, theconsumed energy can be determined from the consumed power during thetimes that the each device is in the sleep and wake states. E_(end) _(—)_(devices) is the sum of the consumed energy for all of the end devices(N) and can be expressed as:E _(end) _(—) _(devices)=Σ_(i=1) ^(N)(P _(sleep,i) *T _(sleep,i) +P_(wake,i) *T _(wake,i))  (EQ. 2)

With some embodiments, an end device can be only in the sleep state orin the wake state, and consequently, T_(sleep,i)=T_(span)−T_(wake,i). Insuch cases, EQ. 2 can be written as:

$\begin{matrix}{E_{{end}\;\_\;{devices}} = {{\sum\limits_{i}^{N}{T_{{wake},i}*\left( {P_{{wake},i} - P_{{sleep},i}} \right)}} + {T_{span}*P_{{sleep},i}}}} & \left( {{EQ}.\mspace{14mu} 3} \right)\end{matrix}$

With some embodiments, all of the end devices may be treated with thesame priority so that each of the end devices is in the wake state forthe same amount of time (T_(wake)) during T_(span). In such a case:

$\begin{matrix}{{T_{wake} = \frac{E_{{end}\;\_\;{devices}} - {T_{span}*{\sum\limits_{i = 1}^{N}P_{{sleep},i}}}}{\sum\left( {P_{{wake},i} - P_{{sleep},i}} \right)}}{where}} & \left( {{EQ}.\mspace{14mu} 4} \right) \\{T_{sleep} = {T_{span} - T_{wake}}} & \left( {{EQ}.\mspace{14mu} 5} \right)\end{matrix}$

While EQs. 4 and 5 express the total sleep and wake times of an enddevice, sleep mode operation can be administered differently overT_(span). For example, central unit 101 can initiate sleep operation ofan end device in a uniform manner over T_(span) or only during times ofrelative inactivity (e.g., during the night time). Also, sleep times fordifferent end devices can be staggered in time to mitigate networktraffic over network 100 when the end devices wake.

With some embodiments, end devices 102-109 may be associated withdifferent priority levels, in which the wake time of a frequently activeend device is in the wake state for a longer period of time than an enddevice that is relatively inactive. For example, if the i^(th) enddevice is assigned to the k^(th) priority level:T _(wake,i) =M _(k) *T _(wake)  (EQ. 6)where M_(k) is a multiplier associated with the k^(th) priority leveland T_(wake) is the base wake time. The resulting T_(wake,i) can then beapplied to EQ. 3 to determine T_(wake).

When the wake and sleep times have been determined at block 901, centralunit 101 can instruct the end devices to operate in the sleep mode atappropriate times during T_(span) at block 902 so that the target energyconsumption of network 100 can be achieved. For example, central unit101 may initiate a request to sleep to end device 102 with apredetermined time or RSM code.

Embodiments of the disclosure may include forms of computer-readablemedia. Computer-readable media include any available media that can beaccessed by a processing device. e.g., processing device 201 or 301 asshown in FIGS. 2 and 3, respectively. Computer-readable media maycomprise storage media and communication media and in some examples maybe non-transitory. Storage media include volatile and nonvolatile,removable and non-removable media implemented in any method ortechnology for storage of information such as computer-readableinstructions, object code, data structures, program modules, or otherdata. Communication media include any information delivery media andtypically embody data in a modulated data signal such as a carrier waveor other transport mechanism.

Although not required, one of ordinary skill in the art will appreciatethat various aspects described herein may be embodied as a method, adata processing system, or as a computer-readable medium storingcomputer-executable instructions. For example, a computer-readablemedium storing instructions to cause a processor to perform steps of amethod in accordance with aspects of the invention is contemplated. Forexample, aspects of the method steps disclosed herein may be executed ona processor on a computing device 101. Such a processor may executecomputer-executable instructions stored on a computer-readable medium.

As can be appreciated by one skilled in the art, a computer system withan associated computer-readable medium containing instructions forcontrolling the computer system can be utilized to implement theexemplary embodiments that are disclosed herein. The computer system mayinclude at least one computer such as a microprocessor, digital signalprocessor, and associated peripheral electronic circuitry.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. An apparatus comprising: at least one memory; andat least one processor coupled to the at least one memory and configuredto perform, based on instructions stored in the at least one memory:obtaining sleep information for a first end device connected to anetwork, wherein: the sleep information is indicative when the first enddevice operates in a sleep mode; the network is connected to a pluralityof end devices; and the plurality of end devices includes the first enddevice; determining a scanning time based on the sleep information;determining whether a response is received from the first end devicewithin the scanning time when the first end device wakes up from thesleep mode; instructing the first end device to initiate sleep modeoperation for a time duration; determining a targeted energy usage forthe network; and determining the time duration of the sleep modeoperation for the first end device based on the targeted energy usagefor the network, wherein the time duration is dependent on a deviceenergy usage of all other end devices connected to the network.
 2. Theapparatus of claim 1, wherein the at least one processor is furtherconfigured to perform: receiving tolerance information from the firstend device, the tolerance information indicative of a clock accuracy ofthe first end device; and based on the tolerance information, adjustingthe sleep information to obtain the scanning time to receive theresponse from the first end device.
 3. The apparatus of claim 1, whereinthe at least one processor is further configured to perform: receiving arequest from the first end device, wherein the request includes statusinformation that is indicative of an operating condition of the firstend device.
 4. The apparatus of claim 3, wherein the at least oneprocessor is further configured to perform: converting the statusinformation to a sleep time value, wherein the sleep time value isindicative of when the first end device operating in the sleep mode. 5.The apparatus of claim 3, wherein the at least one processor is furtherconfigured to perform: determining an action indicator from the statusinformation, the action indicator indicating an action to be initiatedfor the first end device.
 6. The apparatus of claim 3, wherein therequest contains a device identifier and wherein the at least oneprocessor is further configured to perform: converting the deviceidentifier to a location indicator.
 7. The apparatus of claim 5, whereinthe at least one processor is further configured to perform: sending theaction indicator to a display device.
 8. The apparatus of claim 4,wherein the status information contains a code and wherein the at leastone processor is further configured to perform: translating the code tothe sleep time value.
 9. The apparatus of claim 8, wherein the at leastone processor is further configured to perform: receiving translationinformation from the first end device for the translating.
 10. Theapparatus of claim 1, wherein the at least one processor is furtherconfigured to perform: setting the time duration to a predeterminedvalue.
 11. The apparatus of claim 1, wherein the at least one processoris further configured to perform: sending a code indicator to the firstend device that is indicative of the time duration.
 12. The apparatus ofclaim 1, wherein the at least one processor is further configured toperform: prioritizing the plurality of end devices into a plurality ofpriority levels; and determining a wake time of the first end devicebased on a first priority level of the first end device, wherein theplurality of priority levels includes the first priority level.
 13. Theapparatus of claim 1, wherein the at least one processor is furtherconfigured to perform: receiving a battery status of the first enddevice; and adjusting the time duration for the sleep mode operationfrom the battery status.
 14. The apparatus of claim 1, wherein the timeduration is dependent on a total device energy usage of the plurality ofend devices.
 15. The apparatus of claim 1, wherein the network includesat least one router and wherein the targeted energy usage for thenetwork includes a router power consumption for the at least one router.16. The apparatus of claim 1, wherein the network includes a centralprocessing device and wherein the targeted energy usage for the networkincludes a central processing power consumption for the centralprocessing device.
 17. A method comprising: obtaining sleep informationfor a first end device connected to a network, wherein the sleepinformation is indicative when the first end device operates in a sleepmode, the network is connected to a plurality of end devices, and theplurality of end devices includes the first end device; determining ascanning time from the sleep information; determining whether a responseis received from the first end device within the scanning time when thefirst end device wakes up from the sleep mode; instructing the first enddevice to initiate sleep mode operation for a time duration; determininga targeted energy usage for the network; and determining the timeduration of the sleep mode operation for the first end device based onthe targeted energy usage for the network, wherein the time duration isdependent on a device energy usage of all other end devices connected tothe network.
 18. The method of claim 17, further comprising: receivingtolerance information from the first end device, the toleranceinformation indicative of a clock accuracy of the first end device; andbased on the tolerance information, adjusting the sleep information toobtain the scanning time to receive the response from the first enddevice.
 19. The method of claim 17, further comprising: prioritizing theplurality of end devices into a plurality of priority levels; anddetermining a wake time of the first end device based on a firstpriority level of the first end device, wherein the plurality ofpriority levels includes the first priority level.
 20. The method ofclaim 17, further comprising: receiving a battery status of the firstend device: and adjusting the time duration for the sleep mode operationfrom the battery status has changed.
 21. The method of claim 19, whereinthe determining the wake time of the first end device comprises:multiplying a base wake time by a first multiplier associated with thefirst priority level.
 22. A non-transitory computer-readable storagemedium storing computer-executable instructions that, when executed,cause a processor at least to perform operations comprising: obtainingsleep information for a first end device connected to a network,wherein: the sleep information is indicative when the first end deviceoperates in a sleep mode; the network is connected to a plurality of enddevices; and the plurality of end devices includes the first end device;determining a scanning time based on the sleep information; determiningwhether a response is received from the first end device within thescanning time when the first end device wakes up from the sleep mode;instructing the first end device to initiate sleep mode operation for atime duration; determining a targeted energy usage for the network; anddetermining the time duration of the sleep mode operation for the firstend device based on the targeted energy usage for the network, whereinthe time duration is dependent on a device energy usage of all other enddevices connected to the network.
 23. The non-transitorycomputer-readable storage medium of claim 22, wherein thecomputer-executable instructions, when executed, cause the processor toperform: categorizing the first end device as a first priority levelfrom a plurality of priority levels; and obtaining a device wake timefor the first end device from a first multiplier associated with thefirst priority level and a base wake time.